Several parts of the country have been experiencing harsh weather conditions as we move from fall into the early stages of winter. Here in Ohio, recent weather patterns can easily be classified as wet and mild. Don't let the recent run of 50 - 70 degree temperatures lull you into a false sense of security. As sure as the holiday season is winding down and we get set to turn the calendar over to 2016, more traditional winter weather will be here soon enough.
Most cow-calf producers understand that winter weather can pose challenges for them to meet the nutritional needs the cow herd. Changes in temperatures and moisture (rain, sleet, snow, ice, etc.) can significantly impact thedaily nutritional needs of the beef cow. The stage of gestation or lactation of the cow certainly impacts her daily needs regardless of the season. The quality and quantity of forages available to be fed through the winter are generally set at this point unless additional purchases are made.
In a recent issue of Oklahoma State University's Cow-Calf Newsletter, Dr. Glenn Selk reminds producers how weather conditions impact the nutritional needs of the beef cow. He points out that researchers have used the rule of thumb that cows' energy requirements increase 1% for each degree the wind chill is below the 32 degree F lower critical temperature. For example, assume that we have a wind chill of 10 degrees F. The cow's energy requirement would then increase by 22 %. If a cow typically eats 20 pounds of high quality grass-legume mixed hay per day, they would then require 24.4 pounds per day.
Dr. Selk also stated that research has indicated that energy requirement for maintenance of beef cows with a wet hair coat is much greater. Cows that are exposed to falling precipitation and have the wet hair coats are considered to have reached the lower critical temperature at 59 degrees F. In addition, the requirements change twice as much for each degree change in wind-chill factor. In other words, the energy requirement actually increases 2% for each degree below 59 degrees F. Using the same wind chill of 10 degrees F as in the previous example, the cow's energy requirement would then increase by 98 %.
This kind of energy change is not possible by simply feeding more of the same type of feedstuffs. If you have higher quality hay, feed more of that. Also consider supplementing with grain for more energy but make changes gradually to avoid digestive issues. It would be wise to make smaller changes in the diet at the time of weather-related stress and continue any increases when the weather stabilizes to compensate for any energy deficiencies the cow may have experienced.
Another factor to consider is the gestation status of the cow. While a few producers have started calving, the majority of spring-calving cows has transitioned to their last trimester or will soon begin calving. Using a 1,300 lb. mature beef cow as an example, her daily dry matter intake should increase by 6.8 % when transitioning from the middle to last trimester. Another 2.9 % increase in daily dry matter should occur after calving.
Hopefully you have a good handle on the quality and quantity of the forage you have stored for the winter feeding period. If you have not performed a laboratory analysis on the different types of hay that you will be feeding, it is not too late to get this done. If you do not obtain a forage analysis, target your perceived higher quality hay (less mature at harvest or higher legume content) to groups with the highest nutritional demands. First-calf heifers in their last trimester and calving are at the highest risk for nutritional deficiencies and should receive the highest quality feeds. Third trimester and calving mature cows should be prioritized next for better feedstuffs. Bred, dry mature cows in mid-gestation and in adequate body condition are candidates for lower quality feedstuffs.
Hopefully you were able to spend quality time with friends and family during the holiday season. As we start 2016, don't be afraid to spend quality time on nutritional management of the cow herd during the winter.